Core C will support and encourage research into cutaneous epithelial stem cells by providing expertise and training in the characterization and isolation of epithelial stem cells in the hair follicle. The main goals of Core C are to enable investigators to analyze their transgenic or mutant mice for alterations in epithelial stem cells and to encourage translation of mouse work to human skin using a human skin/scid mouse xenograft model. Core C takes advantage of assays and expertise in stem cells found in the core director's laboratory, as well as existing resources and successful cores established at Penn. In particular, Core C will integrate with Penn's School of Medicine Flow Cytometry Core run out of the pathology department and the Xenografting core in the department of medicine that is partly funded through the Institute for Regenerative Medicine. These interactions will assure that investigators will have access to high quality, cost effective services, as well as the scientific expertise necessary to study epithelial stem cells in their research efforts. The stem cell core will offer analysis of hair follicle stem and progenitor cells using a wide variety of standard (label-retaining cell, immunohistochemistry) and cutting edge assays (marker analysis by fluorescent activated cell sorting [FACS],.multipotency testing). Core C will offer functional testing of hair follicle stem and progenitor cells in reconstitution assays. A major part of the core will be to provide training to laboratory personnel so that they can isolate cell populations from the skin and perform FACS analysis and cell isolation using the established Flow Cytometry Core. The human skin xenograft portion of Core C will encourage testing relevance of mouse findings in human skin. The xenograft model is an elegant means to perform preclinical functional studies on human skin that will streamline the development of clinically relevant technologies. Core C will integrate with Core A by using Core A's immunohistochemistry services to assess stem cell markers in tissues. Core C will integrate with Core B by receiving skin for xenografting.